1. Field of the Invention
The present invention relates to an optical head slider for use in an optical head for recording/reproducing information signals to/from a recording medium such as an optical disc, a method for manufacturing the optical head slider, and a recording and/or reproducing apparatus for recording/reproducing information signals to/from a recording medium by the use of an optical head having the optical head slider.
2. Description of the Related Art
Up to now, there have been proposed optical discs, such as a magneto-optical disc and phase change type optical disc, to/from which information signals are recorded/reproduced by irradiating a beam to the signal recording surface thereof. So as to record many information signals to an optical disc to the utmost, attempts to enlarge recording density thereof have been made enthusiastically.
Along with the attempts to enlarge recording density of an optical disc, attempts to improve recording density have been made as to an optical pick up which records/reproduces information signals to/from an optical disc. That is, the optical pick up has reduced its spot size of a beam to be irradiated to the signal recording surface of an optical disc.
Especially, recently, the techniques of a floating type head slider of a hard disc drive have been employed to configure an optical head slider by mounting an optical lens to a sliding member. That is, there is proposed an optical head slider which is floated by a predetermined clearance and slides on the signal recording surface of an optical disc and whose optical lens condenses a beam led by an optical fiber to irradiate the condensed beam to the signal recording surface of an optical disc.
In case such an optical head slider is used in an optical disc drive, the clearance between the optical lens and the signal recording surface of an optical disc can significantly be reduced compared with that which does not use the optical head slider and irradiates a beam from an optical head to the signal recording surface of an optical disc. Thus, a lens of a high NA (numerical aperture) can be used, and the spot size of a beam to be irradiated to the signal recording surface of an optical disc can be reduced.
In the above-described optical disc drive, the optical lens is required to be unitedly mounted to the optical head slider such that the bottom of the optical lens is located at the bottom of the optical head slider which faces the optical disc. The optical lens is fixed at an opening provided at the optical head slider by undergoing glass fusion or adhesion using UV (ultraviolet) curing type organic adhesive.
FIG. 1 shows a sectional view of a conventional optical head slider 100. As shown, the optical head slider 100 has a sliding member 102 which is floated and slides on the signal recording surface of a magneto-optical disc 101 at the time of recording/reproducing information signals to/from the magneto-optical disc 101, and an objective lens 103 which is fixed to the sliding member 102. The sliding member 102 has an optical fiber 104 and a deflection mirror 105 built therein. A laser beam L led by the optical fiber 104 falls on the objective lens 103 via the deflection mirror 105, and is condensed by the objective lens 103, and then falls on a signal recording layer 101a of the magneto-optical disc 101.
The sliding member 102 further has a thin-film coil 106 for applying a magnetic field to the magneto-optical disc 101 at the time of recording information signals, and a terminal 107 which is electrically connected to the thin-film coil 106. The thin-film coil 106 is so located at the lower part of the sliding member 102 facing the magneto-optical disc 101 as to wind around the objective lens 103 to form a thin film. On the other hand, the terminal 107 is formed by filling conductive material into an opening 108 which penetrates the sliding member 102 along the thickness direction thereof such that the end thereof is shared with the end of the thin-film coil 106.
The sliding member 102 is mounted to the end of a supporting arm 109 which is mounted to the optical disc drive. The laser beam L scans the signal recording surface of the rotated magneto-optical disc 101 when the supporting arm 109 is caused to pivot along the radial direction of the magneto-optical disc 101.
Thus configured optical bead slider 100 receives an airflow generated due to the rotation of the magneto-optical disc 101, and is floated by a predetermined clearance from the signal recording surface of the magneto-optical disc 101, while irradiating the laser beam L condensed by the objective lens 103 to the signal recording layer 101a of the magneto-optical disc 101 to record/reproduce information signals to/from the magneto-optical disc 101. When recording information signals, the thin-film coil 106 generates a magnetic field of a predetermined intensity, and applies the magnetic field to a portion of the signal recording layer 101a of the magneto-optical disc 101 to which the laser beam L is irradiated.
The optical head slider 100 is provided with an opening 113 which penetrates the sliding member 102 along the thickness direction thereof, and the objective lens 103 is fit into the opening 113 and fixed to the sliding member 102 by undergoing glass fusion or adhesion using UV (ultraviolet) curing type organic adhesive 110.
The lower part of the optical head slider 100 is made up of the lower part of the sliding member 102, objective lens 103, thin-film coil 106 and adhesive 110. So, at the time of polishing the bottom of the optical head slider 100, there are generated micro-irregularities being of the order of 100 nm to 200 nm due to the hardness difference between their materials.
In case of irradiating a beam of a reduced spot size to the magneto-optical disc 101 by the use of the high NA lens to enlarge recording density, the clearance between the optical head slider 100 and the signal recording surface of the magneto-optical disc 101 becomes significantly small. So, when dust is attached to the micro-irregularities of the floating surface or the bottom of the optical head slider 100, the magneto-optical disc 101 is caused to crash frequently due to the reduced clearance. Furthermore, the dust attached to the floating surface of the optical head slider 100 is burned, and such burned dust cannot be removed or cleaned up even though organic solvent is used.
It is therefore an object of the present invention to overcome the above-mentioned drawbacks by providing an optical head slider of a high reliability which can appropriately record/reproduce information signals to/from a recording medium even though the clearance from the signal recording surface of the recording medium becomes significantly small and of a configuration which can facilitate the manufacturing thereof.
It is another object of the present invention to provide a method for manufacturing the optical head slider easily with high accuracy.
It is yet another object of the present invention to provide a recording and/or reproducing apparatus having an optical head using the optical head slider.
According to the present invention, there is provided an optical head slider including:
a sliding member which is floated and slides on a recording medium at the time of recording/reproducing signals to/from the recording medium;
an optical lens having a spherical surface and a flat surface, which is bonded to the sliding member; and
means for generating a magnetic field, which is mounted to the bottom of the sliding member which faces the recording medium;
wherein the sliding member is made of the same material as that of the optical lens, and the flat surface of the optical lens is bonded to the top surface of the sliding member, so that a sum of a thickness of the optical lens and that of a basal plate becomes the radius of curvature of the spherical surface of the optical lens.
With the optical head slider, the optical lens and sliding member, made of the same material as that of the optical lens, are bonded to each other by the optical contact which does not raise optical problems, and the sliding member configures a part of the optical lens. Thus, the optical head can be manufactured easily and reduced in size.
According to the present invention, there is also provided a method for manufacturing an optical head slider including the steps of:
a first step of bonding an optical lens having a spherical surface and a flat surface to a basal plate which is to be an sliding member;
a second step of bonding a reinforcing block being provided with an opening into which the objective lens is fit to the basal plate;
a third step of polishing the bottom surface of the basal plate which faces the recording medium so that the sum of the thickness of the optical lens and that of the basal plate becomes the radius of curvature of the spherical surface of the optical lens;
a fourth step of polishing the top surface of the reinforcing block so that the sliding member becomes of a predetermined thickness; and
a fifth step of cutting the basal plate into individual sliding members.
With the method for manufacturing an optical head slider, a plurality of optical lenses are positioned and arranged on the sliding member being made of the same material as that of the optical lenses, and the optical lenses and sliding member are so bonded by thermocompression bonding as to be united and optically uniform. Furthermore a plurality of reinforcing blocks each being provided with the opening into which the objective lens is fit are positioned and bonded to the sliding member, and the sliding member is polished so that the sum of the thickness of the optical lens and that of the sliding member becomes the radius of curvature of the spherical surface of the optical lens. Thus, a plurality of optical head sliders can be manufactured in one lot. That is, by undergoing above-described manufacturing process, the optical head slider reduced in size can be manufactured easily with high accuracy. With the manufacturing method, a large quantity of optical head sliders each of a stable quality can be manufactured, which can desirably reduce the manufacturing cost.
According to the present invention, there is also provided a recording and/or reproducing apparatus which has an optical head for recording/reproducing information signals to/from a recording medium,
wherein the optical head has a head slider for scanning the rotated recording medium and an arm for supporting the head slider,
the head slider has a sliding member which is floated and slides on the recording medium at the time of recording/reproducing signals to/from the recording medium, an optical lens which is bonded to the sliding member, and means for generating a magnetic field, which is mounted to the bottom of the sliding member which faces the recording medium, and
the optical lens has a spherical surface and a flat surface.
With the recording and/or reproducing apparatus, the sliding member can appropriately record/reproduce information signals to/from a recording medium even though the size thereof is reduced.
These objects and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.